Transformer construction for inhibiting oil deterioration



Feb. 5, 1946 i PITTMAN 2,394,329

TRANSFORMER CONSTRUCTION FOR INHIBITING OIL DETERIORATION Filed Feb. 26, 1943 2 Sheets-Sheet 1 INVENTOR Feb. 5, 1946. R. R. PITTMAN 2,394,329

TRANSFORMER CONSTRUCTION FOR INHIBITING OIL DETERiORATION Filed Feb. 26, 1943 2 Sheets-Sheet 2 INVENTOR Patented Feb. 5, 1946 TRA s onMEncoNs'mUorIoNroa 1N- HIBI'II'NGIOIL DETERIORATION Ralph -R. Pittman, Pine Bluif,-Ark.

Application-February 26, 1943, Serial No.477,294

2* Claims.

"This invention relates generally to electrical apparatus, such as transformers, 'in which the liquid insulating and cooling medium does not entirely fill the tank in which is contained a'winding or other electrical device.

An object of thepresentinvention is the provision Of a construction for inhibiting deterioration of the'oil used in electrical "apparatus as an insulating and cooling fme'dium by preventing contamination ofthe oil with'moisture and at thesa'me time'in'hibiting oxidation and accompanying I sludging'of the oil.

More specificallyf it is-an object'of'this invention to provide means for collecting at a location removed from the cooling liquid the water vapor which condenses upon the inner 'surface'of the cover 'of an outdoor transformer in" response to the cooling of the cover belowthe viewpoint of the vapor, which usually occurs when relatively cold rain impinges on the outside of the cover, and subsequently utilizing the inherent losses of the transformer for subsequently evaporating the collected condensation and expelling it from the tank.

A further important object is to provide a construction in which the moisture-collecting container provides means for excluding oxygen from the oil, to thereby inhibit oxidizing and sludging of the oil.

With these and other objects in view which will appear as the description proceeds, my invention resides in the novel form, arrangement and construction of the transformer, and the scope of the invention is set forth in the appended claims.

In certain patents, such as the United States Patent 2,146,311, a construction is shown which embodies means for circulating air through the unfilled space within the transformer. Such constructions are effective in removing moisture which adheres to the cover of the transformer, but in so doing the circulating air contacts the oil when the latter is above the temperature of the air, and thereby causes oil sludging due to oxidation products. Such constructions are also ineffective in preventing dropping of condensed water vapor into the oil and upon the winding.

In the drawings: Fig. 1 is a side elevational view of an embodiment of the invention, shown in section; Fig. 2 is a fragmentary section along the line 22 of Fig. l; and Figs. 3, 4, and 5 are respectively a top plan view, a sectional view and a bottom plan view of the moisture collector and evaporator.

Referring in detail to Fig. 1, a tank l0, having a. vertically extending wall, is provided with a cover -I l t a gasket i l 8 being employed'to assure "a tight seal between' these elements. An electrical device'IZ, which maybe a core-and-coils assembly, is contained by the'tan'k I ll, and is electrically connected through the conductors l3 and I 4 to the entrance bushings I5an'd l6 respectively. A non-aqueous cooling and insulating liquidJ22, which may be oil,,part iallyfills the tank l0 to the level 23, the "winding 12. being immersed in the liquid}? in accordance with usual practice.

A containerf24,'of impervious cellular insulating material, shown in more "detail in Figs.'3, 4, and 5, fioats'freely upon, and"substantiallyfcovers the upper'surface oflthe oil. Preferably the container24 is formedof somef'vitreous inorganic insulating n'iaterial, such as glass which has been cellulated-by some suitable process'such that the resulting product "has a density, compared to water equarto 1,:oraboura4ito 0.6. An integral upwardly extending wall 21' extends over' the 'entire periphery of the container; an'd'the integral walls 25 and 26, which encircle the conductors l4 and 13 respectively, extend upwardly to an elevation above the upper edge of the peripheral wall 21, for the purpose of establishing overflow at the edge of the container at points laterally spaced from the winding l2. The passageway through the wall 25 is slightly larger in diameter than the outside diameter of the lower end of the bushing IS, the arrangement being such as to guide vertical movement of the floating evaporator 24 which occurs when the volume of the oil 22 changes due to change in temperature. Preferably, the bottom of the floating container 24 is provided with the diametrically extending ridges 30, and the conductor-encircling ridges 29, for the purpose of increasing the leakage path between the conductors.

A hollow conduit 2| extends upwardly along the vertical wall of the tank In in heat conductive relation with the oil 22, and communicates through the opening 20 in the tank In at the upper and closed end of the conduit 2| with the space 3|, the latter being the space between the floating container 24 and the cover II.

Air enters the lower and open end of the conduit 2|, thence passes upwardly therethrough and into the tank through the openings 20, and thence laterally across-the space 3| and out of the tank to the atmosphere through the vent H. The water vapor accompanying the air in its passage upwardly through the conduit 2| to the space 3| is heated by the electrical losses inherent in the winding assembly, thereby causing it to reach a condition in which it is much farther removed from the dew-point than if it were not so heated. Obviously the heating of the water vapor per se is of assistance in inhibiting its condensation inasmuch as the extent of cooling in order to reach the dew-point has been increased.

In addition, a pronounced chimney effect results from the passage of the heated air from the inlet at the lower end of the conduit 2| outward through the vent IT. The arrangement is such that the air in its passage between the points described, and after being heated during its passage through the vertical conduit 2|, is caused to sweep across the space 3|, and carry out of the tank any condensation which may be suspended on the lower surface of the cover H, or may have dropped from the cover into the container 24.

It may be noted that the container 24, being in contact with the cooling liquid 22, is thereby heated by the inherent electrical losses to facilitate evaporation of any condensation therein contained, and that the electrical losses are thus utilized to perform the dual function of evaporating water from the container and causing an air current of heated air to flow in such a manner that the water vapor is carried out of the tank.

It may also be noted that the container 24 effectively shields the oil 22 from contact with the hot air passing through the tank. In the absence of such shielding, oxidation products would quickly cause sludging of the oil, and the soformed sludge collect in layers over the internal surfaces of the transformer, thereby retarding cooling and reducing the capability of the transformer to carry load.

It is intended that the drawings and description of the specific embodiment of the invention herein presented will be interpreted as illustrative rather than limiting.

I claim:

1. In electrical apparatus which includes a tank having a vertically extending wall, a cooling liquid which expands when heated and contracts when cooled partially filling the tank, an electrical device subject to losses expressed as heat positioned in spaced relationship with said wall and intimately associated with said cooling liquid, a conductor extending upwardly from said device to a point above the surface of said cooling liquid, a vertically movable floating container of electrical-insulating material carried by said liquid, said container being formed with a dish-shaped upper surface including an integral upstanding peripheral flange and an integral upstanding wall encircling said conductor and extending above the elevation of said flange.

2. In electrical apparatus which includes a tank having a vertically extending wall, a cooling liquid which expands when heated and contracts when cooled partially filling the tank and the unfilled portion of the tank containing air, an electrical device subject to losses expressed as heat positioned in spaced relationship with said wall and intimately associated with said cooling liquid, a conductor extending upwardly from said device to a point above the surface of said cooling liquid, a vertically movable floating container of impervious cellular insulating material carried by said liquid, said container being formed with a dish-shaped upper surface including an integral upstanding wall encircling said conductor and an integral upstanding peripheral flange, said encircling wall extending above the elevation of said flange whereby liquid condensation products are discharged from said container in the space between said electrical device and said vertically extending tank wall.

RALPH R. PITTMAN. 

